Flash CS4 - AS 2.0

I'm currently working in Flash CS4 - AS 2.0 and have an annoying problem.

I've got an email link, that when clicked will open up a 'new message' window in whatever email browser you use. For example I use Mail on my Mac, when I click the email link, it opens up Mail, then a new message window to that email address.

The annoying thing is, when I click the link, as well as opening the new message window, for some reason it also opens a black webpage. Even if I've not even got Firefox or Safari running, it'll open one of them up with a black page.

Anyone understand Flash and know why this is? I've used tutorials to do this and followed them bang on but can't for the life of me work out why it decides to open a black webpage.

I have the button linked in the properties panel - mailto:hello@welcometoarrivals.co.uk